479 research outputs found

    Intelligent Self-Repairable Web Wrappers

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    The amount of information available on the Web grows at an incredible high rate. Systems and procedures devised to extract these data from Web sources already exist, and different approaches and techniques have been investigated during the last years. On the one hand, reliable solutions should provide robust algorithms of Web data mining which could automatically face possible malfunctioning or failures. On the other, in literature there is a lack of solutions about the maintenance of these systems. Procedures that extract Web data may be strictly interconnected with the structure of the data source itself; thus, malfunctioning or acquisition of corrupted data could be caused, for example, by structural modifications of data sources brought by their owners. Nowadays, verification of data integrity and maintenance are mostly manually managed, in order to ensure that these systems work correctly and reliably. In this paper we propose a novel approach to create procedures able to extract data from Web sources -- the so called Web wrappers -- which can face possible malfunctioning caused by modifications of the structure of the data source, and can automatically repair themselves.\u

    Adversarial Edit Attacks for Tree Data

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    Many machine learning models can be attacked with adversarial examples, i.e. inputs close to correctly classified examples that are classified incorrectly. However, most research on adversarial attacks to date is limited to vectorial data, in particular image data. In this contribution, we extend the field by introducing adversarial edit attacks for tree-structured data with potential applications in medicine and automated program analysis. Our approach solely relies on the tree edit distance and a logarithmic number of black-box queries to the attacked classifier without any need for gradient information. We evaluate our approach on two programming and two biomedical data sets and show that many established tree classifiers, like tree-kernel-SVMs and recursive neural networks, can be attacked effectively.Comment: accepted at the 20th International Conference on Intelligent Data Engineering and Automated Learning (IDEAL

    Dynamic Set Intersection

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    Consider the problem of maintaining a family FF of dynamic sets subject to insertions, deletions, and set-intersection reporting queries: given S,SFS,S'\in F, report every member of SSS\cap S' in any order. We show that in the word RAM model, where ww is the word size, given a cap dd on the maximum size of any set, we can support set intersection queries in O(dw/log2w)O(\frac{d}{w/\log^2 w}) expected time, and updates in O(logw)O(\log w) expected time. Using this algorithm we can list all tt triangles of a graph G=(V,E)G=(V,E) in O(m+mαw/log2w+t)O(m+\frac{m\alpha}{w/\log^2 w} +t) expected time, where m=Em=|E| and α\alpha is the arboricity of GG. This improves a 30-year old triangle enumeration algorithm of Chiba and Nishizeki running in O(mα)O(m \alpha) time. We provide an incremental data structure on FF that supports intersection {\em witness} queries, where we only need to find {\em one} eSSe\in S\cap S'. Both queries and insertions take O\paren{\sqrt \frac{N}{w/\log^2 w}} expected time, where N=SFSN=\sum_{S\in F} |S|. Finally, we provide time/space tradeoffs for the fully dynamic set intersection reporting problem. Using MM words of space, each update costs O(MlogN)O(\sqrt {M \log N}) expected time, each reporting query costs O(NlogNMop+1)O(\frac{N\sqrt{\log N}}{\sqrt M}\sqrt{op+1}) expected time where opop is the size of the output, and each witness query costs O(NlogNM+logN)O(\frac{N\sqrt{\log N}}{\sqrt M} + \log N) expected time.Comment: Accepted to WADS 201

    Anatomy of the neural fibers at the superior mesenteric artery-a cadaver study

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    PURPOSE Most surgeons perform right-sided semicircular clearance of the superior mesenteric artery (SMA) nerve plexus for pancreatic head carcinoma, presuming a linear course of the SMA nerve fibers. The hypothesis was that the SMA nerve plexus fibers follow a non-linear course, and the goal of the present study was to assess the neural fibers distribution along the SMA. METHODS The course of neural fibers along the retropancreatic and suprapancreatic SMA was assessed in 7 cadavers. RESULTS In the retropancreatic course of the vessel, the main nerve cords branch and form a large number of finer nerve branches performing an anti-clockwise rotation of slightly less than 90° around the SMA. Finer nerve branches are located rather close to the vessel, while the main nerve cords are localized in the loose connective tissue of the peripheral parts of the vascular sheath. Nerve fibers around the suprapancreatic SMA run as two main nerve cords framing the artery on the right lateral-ventral and the left lateral to lateral-dorsal side. CONCLUSION The rotation of the nerve fiber around the SMA indicates that a more radical resection of at least 180° of neural tissue around the SMA might be required to achieve tumor clearance in pancreatic cancer with perineural invasion at the uncinate margin

    Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs

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    Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient’s coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication

    Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs.

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    Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient's coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication

    Many-body theory of pump-probe spectra for highly excited semiconductors

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    We present a unified theory for pump-probe spectra in highly excited semiconductors, which is applicable throughout the whole density regime including the high-density electron-hole BCS state and the low-density excitonic Bose-Einstein condensate (BEC). The analysis is based on the BCS-like pairing theory combined with the Bethe-Salpeter (BS) equation, which first enables us to incorporate the state-filling effect, the band-gap renormalization and the strong/weak electron-hole pair correlations in a unified manner. We show that the electron-hole BCS state is distinctly stabilized by the intense pump-light, and this result strongly suggests that the macroscopic quantum state can be observed under the strong photoexcitation. The calculated spectra considerably deviate from results given by the BCS-like mean field theory and the simple BS equation without electron-hole pair correlation especially in the intermediate density states between the electron-hole BCS state and the excitonic BEC state. In particular, we find the sharp stimulated emission and absorption lines which originate from the optical transition accompanied by the collective phase fluctuation mode in the electron-hole BCS state. From the pump-probe spectral viewpoint, we show that this fluctuation mode changes to the exciton mode with decreasing carrier densityComment: RevTeX 11 pages, 10 figures. To appear in Phys.Rev.B1

    Hygge, Hope and Higher Education: A Case Study of Denmark

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    Higher education institutions have been profoundly reshaped by processes associated with neoliberalism. In this chapter, Larsen outlines the ways in which Denmark has ushered in marketdriven reforms to the Danish higher education system to enhance their institutional competitiveness over the past 30 years. Research on the impacts of neoliberal higher education reforms on faculty is reviewed and the author discusses her experiences (at a Canadian university) with market-driven, accountability reforms. The chapter shifts direction and provides the reader with an overview of the concept of hygge, an idealized Danish term that has connotations of coziness, safety, friendliness, and intimacy. Larsen recounts her experiences as a Canadian academic on sabbatical at a Danish university in 2017, illustrating the ways in which she experienced hygge in the Danish university setting. In the final section of the chapter, Larsen argues that hygge can be viewed as a retreat from the individualism, competition, market stratification and other challenges associated with neoliberalism. Hygge marks out the boundaries between the cold and heartless market-place and the warm and cozy home, and despite critiques that is instantiates exclusions, hygge offers hope to resist the alienation associated with neoliberalism and provide an alternative ethos for close and safe social relations within academia
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